Phase dissolution of γ-Mg17Al12 during homogenization of as-cast AZ80 Magnesium alloy and its effect on room temperature mechanical properties
Abstract
As-cast AZ80 Mg alloy contains α-Mg, partially divorce eutectic of α and γ (Mg17Al12), fully divorce eutectic of α and γ, and lamellar eutectic of α and γ phases. During homogenization, second phase (γ-Mg17Al12) gets dissolved can change the mechanical properties. Therefore, the aim of the present work is to bring out the kinetics of dissolution of γ phase and evaluate its effect on mechanical properties. Microstructure evolution during homogenization was investigated as a function of time for 0.5 to 100 h and at the temperatures of 400° and 439°C. In as-cast state, this material was found to contain 70% α-Mg and 30% eutectic phase. With increasing homogenization time, dissolution of lamellar eutectic occurs first which is followed by dissolution of fully divorce eutectic and partially divorce eutectic. The dissolution kinetics of γ phase was analyzed based on the decrease in its volume fraction as a function of time. The time exponent for dissolution was found to be 0.38 and the activation energy for the dissolution of γ phase was found to be 84.1 kJ/mol. This dissolution of γ phase leads to decrease in hardness and tensile strength with increase in homogenization time.
- Publication:
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Magnesium Technology 2012
- Pub Date:
- 2016
- DOI:
- 10.1007/978-3-319-48203-3_96
- Bibcode:
- 2016mt12.book..543K
- Keywords:
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- Materials Science